OK, I finally have time to respond to Hoosier's 2 excellent points. First regarding the constitutionality of limiting high cap magazines:
I want to commend Hoosier because he is the first person I have read, here or elsewhere, to attempt a specific argument as to why limiting magazines would violate the 2nd Amendment. Everyone else has argued that it violates the "spirit" of the 2nd Amendment, which is an ambiguous notion which could be used to argue against ANY gun restrictions (in fact, that is the whole purpose of that argument) but which can never be used in an actual court of law, much less the Supreme Court. Hoosier, however, argues that magazine limitations contradict the Heller decision, in which trigger locks were deemed to be unconstitutional.
Now let me say first that I think that trigger locks are a stupid idea, that they do nothing to increase public safety, and are a prime example of government overreach. That being said, I'm not sure I agree with the Supreme Court decision that imposing such locks are unconstitutional. It was a 5-4 decision, and the justices opposed to it are people whose opinions I respect very much. But in any case, it was a decision, and Hoosier asks, if we limited magazines to 1 bullet, would it be the same as trigger locks? And if my answer is yes, presumably this principle means we cannot place any limitation on magazines without also violating the 2nd Amendment. A strong, direct challenge to my position.
My answer to Hoosier is yes, imposing a magazine with 1 round only would be, per Heller, a violation of the 2nd Amendment. But that does not mean there can be no limitation whatsoever. The principle here, under the 2nd Amendment, is the phrase "well-regulated". Meaning that we can apply some common sense to regulation. Placing a 1 bullet limitation on guns is beyond "well-regulated" and infringes on gun rights; however, placing a 10 bullet limitation on guns is well within the limits of "well-regulated". If we argue that NO limitation can be placed on magazines, then what is the purpose of "well-regulated"? It becomes meaningless. And, I know we have brought this up before, but if we argue that no limitation can be placed on magazines, then the logical inference is that no limitation can be placed upon any kind of firearm, including fully automatic weapons, rocket launchers, etc. Is that what the Founding Fathers intended? I don't think so.
Therefore, my position is that the "well-regulated" clause of the 2nd Amendment allows to place REASONABLE limitations on guns, such as a 10 round limit on magazines, but does not allow us to place UNREASONABLE limitations on guns, such as a 1 round limit on magazines.